Maybe a silly question...
Does the O2 sensor operate when the vehicle is on gas?

I would say so as I had to have mine replaced for my gas system to work

It depends if it's computer controlled, if it has a stepper motor then yes it does work on the LPG side of things, otherwise no it doesn't.

How would I know if it has a stepper motor (not sure what that is)? I'm still on the waiting list to get my car converted (another 2 months hopefully)...

If your getting a conversion, then yes, the o2 sensor will be used. Its been a legal requirement for some time now.

If you had a much older conversion (up to around 92/94 I think) you could still get away without a computer. Required since tho

Nigel

i have a '90 ea wagon with a CFI 3.9 and 4 speed auto. it has an lpg set upon it. simple mixer job. it was always ok on gas. 500km/65L. but shocking on petrol. one day, i saw oxy sensors on special and put one in. petrol economy improved out of sight, but so did gas ! the setup only has a screw adjustment for max fuel. the only change was a new oxy sensor. it now just about does 600km to 65L. this is driven sensibly on the highway. 100-110 km/h.